One bad night won't kill your power. But it will lie to you.

You had a bad night. Alarm goes off. You feel heavy. The legs feel like concrete before you even clip in.

So you skip the session. Or you soft-pedal through it, convinced you have nothing today.

Here is what is actually happening.

A 2025 study published in the European Journal of Applied Physiology put 26 amateur cyclists through a fascinating test. After 25 hours of total sleep deprivation, they completed 40 minutes of moderate-intensity riding followed by a 20-minute time trial. Then they did it again after one night of recovery sleep.

The results challenge what most of us assume about bad sleep and performance.

1. High-intensity output was not affected.

Sleep-deprived cyclists produced the same power in their time trial as the control group. Their legs were not weaker. Their muscles were not impaired. The engine was still there.

2. Moderate-intensity effort felt significantly harder.

The same steady watts felt worse. Perceived exertion climbed even though the actual workload had not changed. Sleep deprivation did not reduce what they could do. It changed how hard it felt to do it.

3. One night of recovery sleep restored everything.

After a single normal night of sleep, perceived exertion returned to baseline. The mismatch between effort and perception disappeared. One good night was enough to reset the system.

What to do with this

If you race or do hard group rides:
Know that your body can still produce when it matters, even after a rough night. The risk is not that your legs fail. The risk is that you talk yourself out of the effort because your brain is amplifying the cost. Push through the warm-up. Reassess after 15 minutes, not before.

If you train big hours:
This is where poor sleep compounds. Moderate-intensity work is the backbone of endurance training, and if every steady ride feels harder than it should, you will either cut sessions short or accumulate unnecessary mental fatigue. Protect your sleep to protect the quality of your easy riding.

If you are time-capped:
You cannot afford to waste sessions. If you slept badly, do the session anyway, but adjust expectations around how it feels, not what the power file says. Your output is likely closer to normal than your brain is telling you.

Bottom line: A bad night does not take away your fitness. It distorts your perception of it. And one good night gives it all back.

Reference: Gattoni et al. (2025). The effects of one-night sleep deprivation and one-night recovery sleep on endurance cycling performance. European Journal of Applied Physiology.

On my mind

I have a confession.

I know sleep matters. I talk about it constantly. I have read the studies. I coach people to prioritise it. And I still cannot get myself to bed on time the night before an early ride.

It is the most ridiculous thing. I will sit there at 9:30pm knowing full well the alarm is set for 5:30am, knowing I need to be on the bike by 5:45, knowing how I will feel if I only get six hours. And I will just... not go to bed.

It is not that I am doing anything important. Half the time I am staring at my phone or watching something I have already seen. It is not productive. It is not even enjoyable. It is just resistance.

And then the alarm goes off and I am in this no-man's land. Too tired to feel good about it, but too stubborn to skip it. So I ride. And I tell myself I will nap later. I never nap later.

The thing I have started doing, which actually helps, is removing the next day from the equation entirely.

Instead of thinking "I need to go to bed early because I have a ride at 6am," I just focus on one task: be in bed by 9:30. That is it. Not "get enough sleep for the ride." Not "optimise recovery." Just get in bed.

It sounds stupidly simple. But when I frame it as its own job, separate from the morning, it works more often than not. The ride takes care of itself. The energy takes care of itself. I just need to get horizontal.

Sometimes the biggest performance lever is not a better interval session or a smarter race plan. It is just doing the boring, obvious thing that you already know you should be doing.

Get to bed.

Damian